The invention relates to a weight measuring method and apparatus thereof.
An electronic weight measuring apparatus is known which includes a load cell generating an analog signal corresponding to the weight of load, a filter for removing an AC component of an output signal of the load cell, an amplifier for amplifying an analog output signal of the filter, an analog to digital converter for converting an analog signal supplied through the amplifier into a digital signal, a memory for storing digital data from the A/D converter, a data processor for producing weight information corresponding to the weight of load applied to the load cell on the basis of the digital data stored in the memory, and a display device for displaying the weight information from the data processor. The output voltage of the load cell used as a weight sensor is very small, i.e. several .mu.V, and a mechanical damper for absorbing vibration can not be adapted for it. Therefore, the load cell is sensitive for extremely small vibration and is easily affected by noise, thus leading to instable display.
A digital type electronic weight measuring apparatus commercially available has a measuring range from 10 kg to 30 kg, for example, with a scale of 5 g divisions. In the weight measuring apparatus, when the weight of load to be measured is 502.5 g, for example, its display instably fluctuates between 500 g and 505 g.
In order to prevent such a fluctuation of display, the digital data from the A/D converter is sampled, and the way of variation in values of three digital data sampled continuously is observed to select a proper digital data from the three. However, this method fails to substantially eliminate the effect of noise signals and to provide sufficiently high reliable digital data.